Cap for a stamp



FIG. 1 is a perspective view of a cap for a stamp, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof; and,

FIG. 6 is a top view thereof.

The broken lines in the figures that are immediately adjacent to the shaded areas, and define unshaded regions, represent the bounds of the claimed design, while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design. 

The ornamental design for a cap for a stamp, as shown and described. 